Usually displayed on a webpage that either doesn’t exist or is unavailable at the address you gave.

A type of Broadband using your phone line. BT for example use ADSL. Asymmetric because its faster from Internet to computer than the other way round.

A slot on a computer’s motherboard for a graphics card. Generally obsolete now and replaced by PCIe (PCI Express).

A popular operating system made by Google for Smartphones and Tablets.

Software (usually but not always on a Smartphone or Tablet) for carrying out a particular task. Another word for a program really.

A file sent by email is “attached” to the email. An attachment can be a picture, a document, a program or any other type of file.

A measure of total amount of data transferred over a period of time, often used to measure how busy a website is. A webhost will usually base its charges on the bandwidth a website uses, ie how much data per month is requested from it.

A system that examines biological things like fingerprints or Face ID, usually for security purposes. Apple’s iPhone 5S was the first Smartphone to use this technology.

A program built into every PC for setting up very basic things, like how many hard and floppy disks you have and what type they are; the first thing that loads when you start your PC.

The smallest unit of information in a computer, can either equal 0 or 1. Eight bits equal one byte.

A short range wireless data communication system for smartphones and other computing devices. However Bluetooth devices from different manufacturers wouldn’t always communicate with each other reliably, so it hasn’t really taken off as the industry had hoped, and it is now under threat from faster wireless technologies (see Wi-Fi).

Usually used to mean “start up the computer”. Literally, the process of loading up the operating system and getting the computer ready for use. See Reboot

A measure of how quickly information is being transferred, usually via a modem or network. Divide by ten to get an approximation of the number of characters per second (cps). See alsoKbps, Mbps.

A program used for viewing World Wide Web pages on the Internet. Usually available free for download. Popular browsers include Internet Explorer (IE), which is built in to Windows, Mozilla Firefox, and Google Chrome. The most popular browser on Apple devices is Safari.

A temporary storage area for data, often used to “smooth out” incoming audio or video streams. Several seconds worth of material is stored in the buffer and it is then played back from there, so that if there is a brief interruption in the stream your music or video doesn’t stop.

A basic unit of measurement for pieces of information; the space required to store one character. See also Bit, Kilobyte, Megabyte,Gigabyte, Terabyte.

A temporary storage area for frequently or recently used data, either in memory, on your hard disk or the internet. For example, if you go back to a webpage you have recently visited, your PC will usually be able to display it from the internet cache on your hard disk, so it won’t need to download it from the internet again.

A temporary storage area in Windows. When you cut (Ctrl-X) or copy (Ctrl-C) highlighted text, documents or whatever in Windows they are sent to the clipboard; when you paste (Ctrl-V) they are copied from the clipboard to the cursor position. Sending something to the clipboard automatically overwrites its previous contents.

Remote storage via the internet, or sometimes just the internet in general. Called “the cloud” because you don’t know where your data is physically located, it’s just out there somewhere.

Data stored on a disk is spread across a number of clusters, small physical areas on the disk. How big they are depends on the way the disk is formatted.

A small piece of computer code that tells the computer how to decode particular types of information, usually video files. If your video player won’t play a particular format, you can usually download and install a codec which will tell it how from the internet.

A way of making files smaller, either to fit into restricted storage space or to speed up transmission over the Internet. Popular compression standards include JPEG and GIF for pictures, MP3 for music files,MPEG, MP4, AVI and MOV for movie footage, and zip for just about everything else.

A small data file stored on your computer by a website, in theory to allow it to “remember” your preferences, but in practise mostly used to track which adverts you have seen. You can set most browsers to reject all cookies, or to ask your permission before storing them, but this can generate multiple error messages on some websites and is generally more hassle than it’s worth – they are pretty harmless.

An internet service that converts a human web address such as www.harpendencomputerservvices.com into the numeric address that computers use, called the IP address. “Can’t resolve DNS” usually means that this conversion has failed and therefore the website can’t be found.

An internet address owned by a company, organisation or individual, such as harpendencomputerservices.co.uk, nasa.gov or bbc.co.uk.

A small program used by the operating system to control hardware such as a sound or video card. Often downloading the latest driver for a device from the manufacturer’s website will improve its functionality.

PC processors which have two complete processors on the same chip, allowing computers to handle multiple tasks faster. See also quad-core.

A special type of connector for computer monitors, particularly flat panels.

Electronic mail – A way to send messages between computers, or more to the point their users, either over a network or the Internet. E-mail is usually just text, but can have pictures or other files attached.

Coding data so that it can’t be read by hackers etc when transmitted over the internet. For example, any reputable website selling goods by credit card will encrypt your credit card number and personal details.

The system used to connect computers to a network or the internet with a physical cable, including most broadband internet connections. Usually much faster than a wireless connection.

The most popular spreadsheet program for PCs, part of the Microsoft Office suite.

A file which is usually the main part of a program. A program may consist of just an exe file and nothing else, or there may be dozens of files, including more exes.

A sort of index of where data is stored on a hard disk, used by the operating system.

Originally a dedicated computer between you and the internet, preventing hackers, spammers and similar undesirables from taking over your PC. Now often just a program running on your PC, performing the same task. Recent versions of Windows have one built-in as do most home Routers.

A technology for displaying animations (mostly) on webpages, created by the Macromedia Corporation. The Flash Player is a plugin which enables internet browsers to display the animations.

A way of transferring files to or from an internet server. Often how you upload web pages to the internet

Gigahertz – billions of cycles per second. Often used as a measurement of a PC processor chip’s speed and power, with bigger numbers meaning a bit more speed, and a higher price. 1000 MHz = 1.0 GigaHertz. See also MHz.

Unit of measurement for pieces of information : approximately 1 billion bytes, 1 million kilobytes, or 1000 megabytes. Hard disk sizes are usually measured in gigabytes. Often shortened to “GB”, “Gig” or just G.

A computer’s main (and fastest and most convenient) storage for programs and data. Originally named to distinguish it from floppy disks.

A type of PC hard disk, now obsolete, the foreunner of EIDE. Superseeded by SATA.

A unique number assigned to any computer connected to the internet, including yours, in the format 255.255.255.255. Each of the four blocks of numbers can be any value from 0 to 255. They can either be assigned permanently (“static IP”) or per session (“dynamic IP”). Most ISPs assign them dynamically, ie when you connect to the internet.

A programming language used to create small programs calledapplets, often to produce special effects on web pages.

A measure of speed of information flow, usually over a modem. A Kilobit is a thousand bits. See also bps,Mbps.

Unit of measurement for pieces of information : actually 1024 Bytes (characters), but in practice almost always rounded down to 1000. Often written as just K, eg 250 K is 250 Kilobytes (250,000 bytes/characters – well not exactly, but close enough). See alsoMegabyte, Gigabyte, Terabyte.

A network of computers connected together, usually in a single department or building. See also WAN.

A rival PC operating system to Microsoft Windows, but unlike Windows it is “open source”, which means that anyone can create their own version of it without having to pay royalties, and requires a much less powerful computer. Initially required a lot of technical knowledge, but is rapidly being made much more user-friendly.

Apple’s equivalent to the PC. Apple manufacturer both the Hardware and the Software which is currently unique in the industry.

The unique serial number of an Ethernet card, required for connecting a PC to a network. (Nothing to do with Apple Macs, despite the name).

A catch-all term for software installed by stealth onto a PC for malevolent purposes (hence the name). These may include displaying unwanted ads (adware), installing software you didn’t ask for, or spying on your activities (spyware) and reporting them back to the culprit so that he can steal your bank account, address book etc.

A measure of speed of information flow over a network (and if it’s measured in Mbps, it’s reasonably quick.) A Megabit is one million bits. See also bps, Kbps.

Unit of measurement for pieces of information : approximately 1 million bytes or a thousand kilobytes. Often shortened to Meg or just M. See also Gigabyte, Kilobyte, Byte.

A million pixels. Often used to measure the quality of digital cameras : the higher the number the better the camera.

Random Access Memory is the temporary location your computer stores information. Put basically, the more you have the faster your computer goes. We can upgrade your RAM for you, call us for a quote.

Millions of cycles per second. Most often used as a measurement of a PC processor chip’s speed and power, with bigger numbers meaning more speed and a higher price. See also GHz.

A device which allows you to use an ordinary phone over a telephone line set up for an ADSL internet connection. Sometimes just called a filter.

By far the largest software provider for PCs, they created Windows, Microsoft Office (which includes Word, Excel, Access and Powerpoint), Internet Explorer, Outlook and many other widely used programs.

The main circuitboard in the computer – all the other bits and pieces are plugged into it.

A very popular standard for compressing audio and particularly music files down to a reasonable size with little or no perceptible loss of quality, and the files created using it – “an MP3” is an audio file. See MPEG, Compression.

A set of standards for compressing video and audio files, and the committee that came up with them. Also, often used to mean movie files created to the MPEG standard.

An internet server which translates the alphabetic web addresses favoured by humans into the numeric ones used by computers.

A smaller version of the popular laptop computer format.

A way of linking several computers together so that their users can share resources such as printers and documents, often via a central computer called a server. See also LAN, WAN, Ethernet.

An Expansion card which lets a PC communicate with a network or use a broadband internet connection. Almost all modern NICs are Ethernet cards

A portable PC, with system unit, screen and keyboard in one portable package. Also called a laptop.

A company that actually builds computers, as opposed to just retailing them. “OEM software” is ordinary software bought in bulk at a discount by the OEM and pre-installed on a new machines, usually without printed manuals. OEM software cannot legally be sold separately from a computer, so when offered for sale at huge discounts is either pirated, or not what it claims to be.

Every computer has an operating system, which is a sort of master program that runs automatically when you switch the computer on, and continues running till you switch off. The most widely used PC operating system is Microsoft Windows. Apple’s operating system for computers is called OSX.

Originally just short for “personal computer”, PC is now an industry standard, partly evolved in the marketplace, partly agreed by a committee of the major players in the computer industry

A standard for PC expansion cards, currently the most popular in desktop PCs. A “PCI slot” is a socket on the motherboard for such cards. Largly obselete now, replaced by PCIe.

A special type of PCI with faster data transfer. Popular for graphics cards, replacing AGP in most new computers.

A popular document format, used mainly for online computer manuals, which retains the look of a printed book onscreen. PDFs are created using Adobe Acrobat, but can be read and displayed by many different programs including Internet Explorer.

A protocol for transmitting and receiving email.

PC processors which have four complete processors on the same chip, allowing computers to handle multiple tasks faster. See alsodual-core.

A way of connecting multiple hard disks together so that a computer sees them as one very large, very fast disk instead of many smaller ones, or to add redundancy so that if any disk in the array is physically damaged, the others have a copy of all the data and nothing is lost. Often called a “RAID array”, even though the acronym already contains the word array. Mostly used on network servers.

A file on Windows PCs which contains all the settings for the PC and its software. Can be edited by the user, but this should only be done as absolutely a last resort, as it is possible to trash the operating system if you don’t know what you are doing.

Loosely speaking, the quality of an image. When printing or working with images, the resolution is usually measured in Dots Per Inch (dpi) – the more dots per inch, the higher the quality of the image but the larger the file needed to store it. In Windows, the screen resolution is how many pixels fit on the desktop, for example 800 x 600 or 1024 x 768 – the former makes images, icons etc look bigger, but the latter means you can fit more of them on the screen.

A device used to connect networks together, for example so that several PCs can share one internet connection.

A cut-down version of Windows which you can launch instead of the full version for troubleshooting purposes.

A high speed standard for connecting hard disks to your computer, replacing EIDE on most new computers.

A computer at the centre of most networks which provides files and other services to other computers. Also known as a file server.

Unsolicited bulk advertising, usually via email. Originally a name for mass postings to Usenet newsgroups advertising products or services, regardless of their relevance to the newsgroup. (The name comes from a famous Monty Python sketch in which every conversation is interrupted every few seconds by people shouting “spam spam spam” at the top of their voices). Sending spam is illegal in most jurisdictions. A spam filter is a program designed to automatically remove spam from your email before you see it.

Programs, typically installed by stealth, which record what you do on your PC and send reports to criminals, allowing them to steal your bank details, passwords and so on. See also Malware.

A technology that replaces the conventional hard disk, particularly in laptops, with a device that behaves exactly like a hard disk but uses memory instead of magnetic storage. It is very much faster than even the fastest hard disks and is now standard on high-end laptops and notebooks, and often retro-fitted into PCs to imporve their performance.

An area on the righthand end of the Windows Taskbar which displays icons representing TSRs presently running, usually at least a loudspeaker which represents the volume control for the soundcard, and a clock. Programs in the Sytem Tray are often but not always launched from the StartUp folder.

A common protocol(language) which a computer can use to communicate with other computers, particularly on the internet.

Unit of measurement for pieces of information : approximately 1 trillion bytes, 1 billion kilobytes, 1 million megabytes or 1000 gigabytes. That’s a lot of data.

A program similar to a virus which is disguised as something harmless like a game, but when launched actually sabotages the computer on which it is running.

A standard type of connection port, used to attach extra devices such as a scanner to a computer. Standard on new PCs from around 1998. USB 2.0 and 3.0 are faster versions of the same thing. Almost all PCs now use USB to connect the mouse and keyboard as well as other peripherals. USB-C is now a well recognised symmetrical connector, similar to Apple’s own ‘Lightning’ connector.

A program that has been deliberately created to cause computer problems, usually minor ones as a prank, but occasionally very nasty ones indeed, such as erasing your entire hard disk. Viruses were originally designed to attach themselves to programs on a disk, and then “hide” in the computer’s memory once the host program is executed, and “infect” every disk they come across. Some types of virus (such as the famous “I love you”) propagate by email, disguised as an attachment, which is why you should never open an attachment you are unsure of.

Email controlled from a website such as Hotmail, Gmail or Yahoo instead of with a dedicated mail program like Outlook Express or Mac Mail. Many ISPs allow you to access your email both with a mail program and via the Web, so that you can access your email while travelling.

A method of connecting computers to a network without cables, using small radio transmitter/receivers built in to most portable devices and broadband modems. Many hotels and other public locations now offer free WiFi if you have a suitable device, such as a laptop, tablet or smartphone.

The most popular method for compressing files, either for storage or transmission via the internet, widely available as a free download. The compressed files it creates have the extension .zip.